[Veritas-bu] RE: Veritas-bu digest, Vol 1 #2498

Yes, still true today.

Any read operation (import, verify, duplication, restore) is not
controlled by bpsched and therefore will grab an available drive
the moment it sees one, rather than obeying any sort of priority
rules.

HTH
rob

On Fri, Sep 12, 2003 at 07:27:00AM -0600 or thereabouts, David Chapa wrote:
> I believe what we are seeing is not necessarily a higher priority, but a
> byproduct of the fact that a restore does not use the "queue" as of
> today, therefore no mechanism exists to rank its priority.  I believe
> duplication behaves in the same manner.
>  
> Scott:  Do you remember if this is still true in v4.5?  I know it was in
> 3.x.
>  
> David
>  
> -----Original Message-----
> From: scott.kendall AT abbott DOT com [mailto:scott.kendall AT abbott DOT 
> com] 
> Sent: Thursday, September 11, 2003 1:34 PM
> To: Goldfarb, Josh
> Cc: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: Re: [Veritas-bu] RE: Veritas-bu digest, Vol 1 #2498 - 1 msg
>  
> 
> I've actually heard this before as well (or maybe read it somewhere),
> but it is only when the drive becomes available... 
> 
> In an MPX situation, when one job ends, if another queued job can MPX
> onto the same tape (storage unit, retention, MPX values allow it) that
> queued job will go active instead of the higher priority job.  The fact
> of the matter is, during most backup windows, there is almost always a
> job that can do this and dozens or even hundreds of jobs can complete
> this way before the tape drive actually becomes available for a higher
> priority job. 
> 
> This occurs, not only with restores, which are supposedly a priority
> over backups, but also with higher priority backups. 
> 
> It appears that there is a fundamental flaw in the way priorities are
> handled, but how do you do it better?  I don't know if I would want a
> drive with 5 active jobs MPX'ing to it, to go down to 4, 3, 2, 1 until
> it is 0 and becomes available (this could take some time, at which point
> the drive is working at partial capacity and queued jobs are just
> sitting there), just because a higher priority job is queued up. 
> 
> Stopping (or pausing) a backup and making the drive available to be used
> for a restore and then continuing a backup later is nice, but it doesn't
> address the issue with lower priority backups going active over higher
> priority backups if the higher priority backup doesn't use the same
> storage unit or retention or doesn't have a high enough MPX value. 
> 
> Leaving unallocated (from a Storage Unit's perspective) tape drives
> isn't always an option in an SSO environment with a high percentage of
> SAN Media Servers. 
> 
> 
> - Scott 
> 
> 
> 
>  
> "Goldfarb, Josh" <Josh.Goldfarb AT blackrock DOT com> 
> Sent by: veritas-bu-admin AT mailman.eng.auburn DOT edu 
> 09/11/2003 07:12 AM 
>         
>         To:        <veritas-bu AT mailman.eng.auburn DOT edu> 
>         cc:         
>         Subject:        [Veritas-bu] RE: Veritas-bu digest, Vol 1 #2498
> - 1 msg
> 
> 
> 
> IT is my understanding that a restore is the highest priority.  If all
> your drives are taken from backups it will grab the next available
> drive. 
> 
> 
> -----Original Message-----
> From: veritas-bu-request AT mailman.eng.auburn DOT edu
> [mailto:veritas-bu-request AT mailman.eng.auburn DOT edu] 
> Sent: Wednesday, September 10, 2003 1:02 PM
> To: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: Veritas-bu digest, Vol 1 #2498 - 1 msg
> 
> 
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> Today's Topics:
> 
>   1. Re: Prioritizing Restores over Backups in 4.5 (Wayne T Smith)
> 
> --__--__--
> 
> Message: 1
> Date: Wed, 10 Sep 2003 09:38:34 -0400
> From: Wayne T Smith <WTSmith AT maine DOT edu>
> To: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: Re: [Veritas-bu] Prioritizing Restores over Backups in 4.5
> 
> Hart, Charles wrote, in part:
> 
> > Oh.. I can't hold it in.  I'm a fairly new user to Netbackup 4.5FP#, 
> > have been using TSM for a couple years, and I find this troubling.  In
> the TSM world Restores Always take precedence.  If another task is using
> a drive in TSM, TSM will make a drive available, then once the restore
> is complete TSM will know where it left off on the prior task.
> > 
> > I feel like I've just traded in my Cadillac for a KIA.....
> 
> You did!  Join the club.  Nothing is perfect, though that Cadillac was 
> pretty good.  ;-)
> 
> cheers, wayne
> 
> 
> 
> --__--__--
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